Device for the fractionation of three-phase mixtures



J. BUCHLER Jun 30, Q 1959 DEVICE FOR THE FRACTIONATION OF THREE-PHASE MIXTURES Filed April 23, 1956 2. Sheets-Sheet l INVENTOR.

QJOSEPH BUCHLER wwfi AGENT June 30, 1959 J. BUCHLER 2,892,688

DEVICE FOR THE FRACTIONATION OF THREE-PHASE MIXTURES Filed April 23,- 1956 2 Sheets-Sheetfi I JOSEPH BUCHLER INVENTOR.

AGENT DEVICE FOR THE FRACTIONATION OF TIREE-PHASE lVIlXTURES Joseph Buchler, Fort Lee, NJ.- Application April 23,- 1956, Serial No. 580,022

9 Claims. c1. 23-2705 My present invention relates to a method of and to a device for the recovery of a desired component from a mixture of substances having an aflinity for different solvents which are immiscible with one another, a procedure sometimes referred to as fractionated extraction.

Heretofore, fractionated extraction has been practiced with combinations of two solvents, respectively termed the fixed (or lower) and the mobile (or upper) phase, by using a series of tubes each partly filled with fixed phase and transferring mobile phase progressively from one tube to the other.

Although various arrangements are known for selectively removing one of two phases from a tube, no practical way has yet been found for utilizing the principle of fractionated extraction with more than two solvents. It can be shown, on the other hand, that the theoretical yield of a three-solvent system is greatly superior to that of the conventional two-solvent system, both in terms of ultimate extraction ratio and of the speed of recovery of a given proportion of a particular fraction.

It is, accordingly, the principal object of my present invention to provide a method of and means for enabling ready separation of three immiscible solvents for the purpose set forth.

A more particular object of this invention is to provide means for interconnecting a plurality of tubes in a cascade array in such manner as to obtain two mobile phases moving over diiferent paths through the array, whereby two distinct fractions may be simultaneously separated out in either the two mobile phases or the fixed phase and one mobile phase, the residue being retained in the remaining phase.

One of the dilficulties to be solved in designing a device of the character set forth, adapted to enable the separation of three or more immiscible solvents, is the problem of providing a suitable receptacle (such as a glass tube) with enough inlets and outlets for the admission and the Withdrawal of the several mobile phases while locating these inlets and outlets in such manner that no liquid can pass through them during the preliminary tilting or shaking of the receptacle required to insure proper initial distribution of the multi-fraction sample throughout the various solvents. To accomplish this, in accordance with one of the features of the instant invention, I provide a pair of substantially parallel, elongated vessels or tubes having their facing sides formed with a plurality of apertures; the apertures of the first, preferably longer, vessel include one or more entrance apertures and one exit aperture, those of the second vessel including two exit apertures and one entrance aperture joined to the exit aperture of the first vessel. The exit aperture of the first vessel is provided nearer to one end thereof but spaced a sufficient distance therefrom to insure retention therein of the suitably proportioned lower or fixed phase when the unit is inclined for a decanting of the other phases, the associated entrance aperture or apertures being positioned near the opposite end of that vessel; the exit apertures of the second vessel, which like the entrance aper- '2 tures thereof are suitably spaced from one of its ends, are located at different levels and so arranged that, upon a tilting of the unit at different angles, one mobile phase will pass through one of these apertures whereas the other mobile phase or phases will leave the vessel by the other aperture.

According to another aspect of this invention, I provide a unit comprising two rigidly joined, substantially parallel tubes linked by a connecting duct, the first or principal tube having a pair of entrance nipples facing in the direction of the second or auxiliary tube, the latter tube having a pair of exit nipples facing in the direction of the first tube and respectively positioned at the levels of the entrance nipples thereof but sufiiciently oifset from these entrance nipples and from each other to enable each exit nipple to be coupled to one of the entrance nipples of two identical units, respectively, forming part of a subsequent stage of a cascade array of which the firstmentioned unit represents all or part of a preceding stage,

Preferably, in an array as set forth above, the exit nipples of the auxiliary tube extend laterally past the main tube on opposite sides thereof and for a sufficient distance so that this main tube occupies a position substantially in line with the auxiliary tubes of the units of the succeeding stage, whereby a particularly compact arrangement is formed. An array of this description can be conveniently mounted in a rack enabling the simultaneous tilting of all the units in the proper manner for the purpose of distribution, transfer and withdrawal.

The invention will be described ingreater detail with reference to the accompanying drawing in which:

Fig. 1 is an elevational view, partly in section, of a unit embodying the invention, comprising a main tube and a somewhat shorter auxiliary tube rigidly joined thereto;

Fig. 2 is an elevational View showing the unit of Fig. 1 in an inclined position in which the mobile phases are decanted from the main tube to the auxiliary tube;

Fig. 3 is an elevational view similar to Fig. 2 but showing the unit in another inclined position to illustrate the withdrawal of the mobile phases from the auxiliary tube;

Fig. 4 is a top plan view of several units as shown in Figs. 1-3 coupled together to form several stages of a cascade array;

Fig. 5 is a top plan view of the unit of Figs. l-3 in combination with a holder serving for the mounting of the unit on a supporting bar;

Fig. 6 is a sectional view, on a larger scale, taken through the holder and the supporting bar on the line 55 of Fig. 6;

Fig. 7 is a top plan view of an entire array of units according to the invention together with a mounting rack therefor; and

Fig. 8 is a fragmentary front-elevational view on the line 88 of Fig. 7. r

The unit 10, Fig. 1, comprises a main glass tube 11 and an auxiliary glass tube 12, both parallel to each other and rigidly interconnected bya glass stem 13. Tube 11, which functions as a mixing chamber, has two entrance nipples 14, 15 and an exit nipple represented by an extremity of a connecting duct 16 Whose other extremity forms the sole entrance nipple of an overflow chamber defined by tube 12. Duct 16, which extends at an upward inclination away from tube 11, has two similarly inclined extensions 17, 18 within tubes 11 and 12, respectively.

The extremities of nipples 14, 15 form female coupling halves which are complementary to male coupling halves formed by the. extremities of the two exit nipples 19, 20 of tube 12. Nipple 19, rising from the top of tube 12 in an eccentric position close to the side facing tube 11,

extends at an inclination opposite to that of duct 16 and terminates at the same level as entrance nipple 15. Nipple 20, whose inclination is roughly the same as that of nipple 19, has an extension 21 entering tube 12 at a point whose distance from the lower end of that tube is the same as the distance of the bottom of tube 11 from the point of entry of duct extension 17; this nipple terminates at the same level as entrance nipple 14. As best seen in Fig. 5, the two nipples 19, 20 pass on opposite sides of the main tube 11.

In operation, tube 11 is filled with three immiscible solvents constituting a lower phase I, a middle phase II and an upper phase III. These solvents will generally be liquids, although it should be understood that they may also include solids, e.g. in powder form, especially as the lower phase I. The volume of these solvents, which in a practical case may be 25 cc. per phase, is so selected that the level thereof will not reach the outlet end of duct extension 18 within tube 12 when the unit is in its upright position shown in Fig. 1, and that furthermore the level of the lower phase I will not reach the inlet end of duct extension 17 in any position as will be apparent from Figs. 1, 2 and 3.

After the solvents and the sample to be analyzed have been introduced into tube 11, the unit 10 is placed on its back with the nipples 14 and 15 pointing upwardly, as shown in Fig. 3 (dot-dash lines). The unit may now be shaken by tilting it at various angles to the horiozntal within a vertical plane defined by the axes of both tubes 11, 12, e.g. as shown in solid lines in Fig. 3. After the contents of the tube 11 have thus been thoroughly agitated, the unit is left to rest so as to allow the several phases to settle out and separate; this may be done in the horizontal, the vertical or some intermediate position of the unit.

For the next step, the decanting of mobile phase II and III, the unit is inclined forwardly as shown in Fig. 2 until the lower edge of extension 17 lies approximately in the plane of the level of fixed phase I. The middle phase II and the upper phase III now pass through duct 16 into tube 12 as indicated by the solid lines and the broken arrow, respectively, in Fig. 2.

Thereafter, unit 10 is brought into the position shown in solid lines in Fig. 3 in which the meniscus at the interface between phases II and III just touches the extension 21 of nipple 20. Upper phase III now flows out through nipple 20, as indicated by a broken arrow, whereupon a further tilting of unit 10 to substantially horizontal position (dot-dash lines) enables the withdrawal of middle phase II through nipple 19 as indicated by the solid arrow. Subsequently, fresh middle and upper phase may be added through nipples 14 and/or 15, followed by a repetition of the same cycle. Eventually, fixed lower phase I may be removed from tube 11 by placing the same horizontally on its face, i.e. with nipples 14 and 15 facing down, if necessary by flushing with a suitable liquid through these nipples.

In Fig. 1 I have also shown a clamp 22 serving as a means for coupling the entrance nipple 15 with an exit nipple 19' of a second unit identical with unit It a like clamp may be used to unite nipple 14 with the exit nipple of still another unit corresponding to nipple 29. Fig. 4 illustrates how, in this manner, an array of tubes can be built up from a first stage represented by a single unit comprising tubes 11:: and 12a; a second stage formed by two units 11b12b and 111b112b; a third stage composed of three units 11c-12c, 111c-112c and 211c-212c; and a fourth stage, of which only the auxiliary or overflow tubes 11d, 111d, 211d and 311d are shown. The clamps 22 (Fig. l) have been omitted in Fig. 4 for the sake of clarity.

Fig. 4 also represents a flow chart illustrating the paths over which the mobile phases 11 (solid arrows) and III (broken arrows) move through the array. It will be assumed that all main tubes originally contain their 4 allotted amount of fixed phase I which remains therein throughout the extraction process; tube 11a also contains initially the mixture to be fractionated. Middle and upper phase are introduced from without into tube 11a as indicated by arrows 11a and IIIa, respectively.

Following the agitation and decanting steps previously described, middle phase from tube 12a is transferred to tube 11b which also receives fresh upper phase from without, e.g. by means of a syringe (not shown), as indicated by arrow IIlb; at the same time, upper phase from tube 12a is transferred to tube 111b to which fresh middle phase is added from the outside as indicated by arrow IIb. Agitation and decanting again takes place, whereupon middle phase from overflow tubes 12!) and 112b is transferred to tubes 11c and 111e, respectively, upper phase from these same overflow tubes being simultaneously transferred to tubes 111s and 2110, respectively. It will thus be seen that the central unit 111c-112c of the third stage receives both mobile phases from the preceding stage but that the end tubes 11c and 211a receive only one phase each, the remaining phase being again added from the outside as indicated by arrows 11c and 1110. In analogous manner it is only necessary to supply fresh middle and upper phase to the main tubes (not shown) associated with the outermost overflow tubes 312d and 12d of the fourth stage, as respectively indicated by arrows 11d and IIId.

Figs. 5 and 6 show how the unit or units of a single stage may be mounted on a supporting bar 23 by means of a holder 24. This holder has a triangular cutout 25 within which the principal tube 11 of a unit 10 is held by friction with the aid of a U-shaped strap 26. A guide pin 27, fastened to bar 23, traverses a hole in holder 24; a sleeve 28, externally threaded, is screwed into bar 23 and traversed by a bolt 29 which threadedly engages holder 24. Rotation of the milled head of bolt 29 in a tightening direction urges the holder 24 into firm contact with the flanged left-hand end (as viewed in Fig. 6) of sleeve 28; thus, the position of the holder, and of the tube 10 clamped therein, relative to bar 23 may be adjusted by a resetting of sleeve 28 through rotation of its hexagonal head upon the loosening of a nut 30 serving to lock this sleeve in position.

It will be understood that with the arrangement shown in Figs. 5 and 6 one or more units 10 may be detachably clamped onto a supporting bar 23 common to all the units of a stage. Fig. 7 shows a set of six such supporting bars 23a, 23b, 23c, 23d, 23e, 23 forming part of a six-stage array. This array represents a further extension of the arrangement described in connection with Fig. 4 and includes a single unit Ila-12a in its first stage, two units lib-42b and 111b112b in its second stage, and so on up to the sixth stage where one of the six units have been indicated at 11f-12f. Principal tube 11) as well as the corresponding tube lle of the preceding stage are visible in Fig. 8.

The bars 23a23f are removably held in a U-shaped frame 31 whose upper flange is engaged by a slotted coupling block 32a32f' and 32a-32f. As particularly shown in Fig. 8 for the right-hand end of bar 237, block 32f is attached to this bar by a screw 33f and is provided with a wingnut 34f for clamping it onto the frame 31. Fig. 8 also shows guide pin 27 bolt 29f and lock nut 30 for mounting the tube 11] on bar 23f by means of holder 24 (Fig. 7), the adjustability afforded by this mounting insuring the achievement of an exact fit of the ball-and-socket joints formed by the extremities of the mating nipples of adjoining stages.

The frame 31 with its bars 23a23f defines a tiltable rack supported by shafts 35, 35" in a pair of bearings 36, 36" on posts 37, 37". Shaft 35 also carries a weight 38, designed to balance the uneven loading of the rack, as well as a crank 39 representative of any means for imparting to the rack the motions described above for the agitation, decanting and transfer operations.

From Fig. 8, which shows the exit nipples 19 20 of the first tube 11] as well as the exit nipple 119f of the second tube 111) of the sixth stage, and also from Figs. 4 and 7 it will be apparent that the number of outlets available in an array with n stages equals 211, or twelve in the particular example illustrated. Half of these outlets carry the mobile middle phase II, the other half carrying the mobile upper phase III. The total number of units in an n-stage array is n(n+1)/2, or twenty-one in the illustrated arrangement. In practice, it has been found convenient to use assemblies of eleven stages or more, resulting in an extraction ratio of almost unity.

My invention is, of course, not limited to the specific embodiment described and illustrated but may be realized in various modifications and adaptations without departing from the spirit and scope of the appended claims. It will be appreciated, for example, that fractionation with four solvents will be possible by decanting the three uppermost (mobile) phases from a vessel similar to tube 11 into a unit and proceeding with the separation of these phases within the latter unit in precisely the manner hereinabove described, and that in analogous manner the number of phases may be further increased, subject only to the availability of a suflicient variety of suitable solvents.

I claim:

1. A device for the fractionation of three-phase mixtures, comprising a plurality of units each having a pair of substantially vertical tubes including a main tube and an overflow tube rigidly connected together, each of said tubes being closed at its ends, each unit being provided with two forwardly facing, horizontally and vertically spaced exit nipples on said overflow tube and with two rearwardly facing, vertically spaced entrance nipples on said main tube, each exit nipple being positioned on the level of a respective entrance nipple, each unit further comprising a connecting duct between said tubes entering the latter at locations above their bottoms, said exit nipples opening into said overflow tube respectively below and above said duct, both of said entrance nipples opening into said main tube above said duct, said units being arranged in a plurality of stages with each successive stage containing one unit more than the immediately preceding stage; and coupling means operatively connecting the exit nipples of each unit of a preceding stage with respective entrance nipples of two units of the immediately succeeding stage.

2. A device according to claim 1 wherein said overflow tube is positioned to the rear of said main tube, said exit nipples extending from said overflow tube on opposite sides of said main tube.

3. A device according to claim 2 wherein said overflow tube terminates below the top of said main tube, said entrance nipples being disposed substantially in a common axial plane of said tubes above the top of said overflow tube.

4. A device according to claim 2 wherein said exit nipples extend inclinedly upwardly from said overflow tube, said duct extending from said main tube to said overflow tube at an inclination opposite to that of each of said exit nipples.

5. A device for the fractionation of three-phase mixtures, comprising a plurality of units each including a substantially vertical main tube and a shorter, substantially vertical overflow tube positioned rearwardly of said main tube and terminating below the top of the latter, each of said tubes being closed at its ends, a connecting duct between said tubes extending inclinedly rearwardly from a location above the bottom of said main tube to a more elevated location above the bottom of said overflow tube, a forwardly facing first exit nipple extending inclinedly upwardly from said overflow tube and opening into the latter above said duct, a forwardly facing second exit nipple extending inclinedly upwardly from said overflow tube and opening into the latter below said duct, the free ends of said exit nipples being horizontally and vertically oifset from each other, said second exit nipple being provided with an extremity projecting into the interior of said overflow tube and terminating above its bottom, said duct being provided with two extremities respectively projecting into the interiors of said main tube and of said overflow tube, and a pair of rearwardly facing, vertically staggered entrance nipples on said main tube above the top of said overflow tube, the free end of each entrance nipple being on the level of the free end of a respective exit nipple, said units being arranged in a plurality of stages with each successive stage containing one unit more than the immediately preceding stage; and coupling means operatively connecting the exit nipples of each unit of a preceding stage with respective entrance nipples of two units of the immediately succeeding stage.

6. A device according to claim 5 wherein said exit nipples extend from said overflow tube on opposite sides of said main tube.

7. A fractionating unit for three-phase mixtures, comprising a substantially vertical main tube and a substantially vertical overflow tube rigidly connected together, each of said tubes being closed at its ends, a connecting duct between said tubes entering the latter at locations above'their bottoms, a pair of forwardly facing exit nipples extending inclinedly upwardly from said overflow tube, said exit nipples opening into said overflow tube respectively below and above said duct, and at least one rearwardly facing entrance nipple on said main tube opening into the latter above said duct.

8. A fractionating unit for three-phase mixtures, comprising a substantially vertical main tube and a shorter, substantially vertical overflow tube positioned rearwardly of said main tube and terminating below the top of the latter, each of said tubes being closed at its ends, a connecting duct between said tubes extending inclinedly rearwardly from a location above the bottom of said main tube to a more elevated location above the bottom of said overflow tube, a forwardly facing first exit nipple extending inclinedly upwardly from said overflow tube and opening into the latter above said duct, a forwardly facing second exit nipple extending inclinedly upwardly from said overflow tube and opening into the latter below said duct, said second exit nipple being provided with an extremity projecting into the interior of said overflow tube and terminating above its bottom, said duct being provided with two extremities respectively projecting into the interiors of said main tube and of said overflow tube, and at least one rearwardly facing entrance nipple on said main tube above the top of said overflow tube.

9. A fractionating unit according to claim 8 wherein said exit nipples extend from said overflow tube on opposite sides of said main tube.

References Cited in the file of this patent UNITED STATES PATENTS 2,040,359 Clayton May 12, 1936 2,170,411 Jacobs et al. Aug. 22, 1939 2,644,743 Clevenger et al. July 7, 1953 2,682,453 Holder et al June 29, 1954 2,739,045 Pfann Mar. 20, 1956 2,754,179 Whatley July 10, 1956 FOREIGN PATENTS 937,733 Germany Jan. 12, 1956 OTHER REFERENCES Schaar and Co. Cat. No. 50, selected Lab. Equipment, USPO, 1950, pp. 169-70.

Treybal: Liquid Extraction, pp. 221-228 (McGraw- Hill), 1951, 1st ed., New York, N.Y.

Wilhelm et al.: A Countercurrent Liquid-Liquid Extraction, Iowa State College Report #458, I.S.C., declassified Sept. 8, 1955, pp. 7-21 and 30-37. 

1. A DEVICE FOR THE FRACTIONATION OF THREE-PHASE MIXTURES, COMPRISING A PLURALITY OF UNITS EACH HAVING A PAIR OF SUBSTANTIALLY VERTICAL TUBES INCLUDING A MAIN TUBE AND AN OVERFLOW TUBE RIGIDLY CONNECTED TOGETHER, EACH OF SAID TUBES BEING CLOSED AT ITS ENDS, EACH UNIT BEING PROVIDED WITH TWO FORWARDLY FACING, HORIZONTALLY AND VERTICALLY SPACED EXIT NUPPLES ON SAID OVERFLOW TUBE AND WITH TWO REARWARDLY FACING, VERTICALLY SPACED ENTRANCE NIPPLES ON SAID MAIN TUBE, EACH EXIT NIPPLE BEING POSITIONED ON THE LEVEL OF A RESPECTIVE ENTRANCE NIPPLE, EACH UNIT FURTHER COMPRISING A CONNECTING DUST BETWEEN SAID TUBES ENTERING THE LATTER AT LOCATIONS ABOVE THEIR BOTTOMS, SAID EXIT NIPPLES OPENING INTO SAID OVERFLOW TUBE RESPECTIVELY BELOW AND ABOVE SAID DUCT, BOTH OF SAID ENTRANCE NIPPLES OPENING INTO SAID MAIN TUBE ABOVE SAID DUCT, SAID UNITS BEING ARRANGED IN A PLURALITY OF STAGES WITH EACH SUCESSIVE STAGE CONTAINING ONE UNIT MORE THAN THE IMMEDIATELY PRECEDING STAGE; AND COUPLING MEANS OPERATIVELY CONNECTING THE EXIT NIPPLES OF EACH UNIT OF A PROCEDING STAGE WITH RESPECTIVE ENTRANCE NIPPLES OF TWO UNITS OF THE IMMEDIATELY SUCCEEDING STAGE. 